n6 BYZANTINE CHURCHES CHAP. or sides. The dome is crowned by a moulded stone cornice of the same type as that of the other walls. In attempting to reconstruct the original form of the church we may first note those features which are evidently Turkish. None of the exterior masonry is Byzantine,, as the use of polished ashlar with fine joints, of pointed arches, and of moulded stone cornices clearly proves. The absence of shafts at the angles of the dome drums and the unrecessed windows are additional proofs of this fact, and we may conclude that the entire exterior was refaced in Turkish times. The diagonal arches under the north and south semi-domes are peculiar. Furthermore, in lobed Byzantine churches the lateral apses project beyond the square outer walls. Here they are contained within the walls.1 Nor are the semi-domes themselves Byzantine in character. The large windows in the dome surface and the lead-covered dormers placed above the flat moulded cornice betray a Turkish hand ; for windows in the dome are universal in the great Turkish mosques, and the method of protecting them on the exterior with wooden dormers is quite foreign to Byzantine ideas. The form of the drums and cornices should be compared with the minor domes of the mosque of Sultan "Bayazid. A careful examination of the building has led to the following conclusions. The lateral semi-domes with their supporting arches are a Turkish addition. The central dome, including the drum, is probably entirely Turkish, and takes the place of an original ribbed dome. The two easternmost domes In the north €aisle7 and those over the inner narthex and the prothesis are also Turkish, and, as already stated, the exterior of the entire building. On the other hand, the eastern apse, the dome arches, the arcade, and the windows above it on the west side of the dome, the inner narthex with the ground vault to the south of it, and the entire outer narthex, are parts of the original building, dating probably from the sixth or seventh century. 1 E.g. S. Elias, Salonica ; Churches on Mt. Athos ; S, Mary of the Mongols,, Constantinople. See plan, p. 279.